Yes you have an A assy gearbox. I'm pretty sure you have partially stripped gear, as I mentioned about "stuttering" or "chattering". The controller does shut off motor after 2-3 seconds in this situation, fortunately.
Getting to the gear is no big deal. Get a helper! Stay clear of the steps and get underneath. Find the connection on the pigtail NOT on the motor, unless you want to get an amputated finger! Staying clear of steps, have helper close door so steps begin to retract. disconnect the connector as step moves so you stop it partially retracted. Now you can get to the pin connecting arm to step.
Some of us have replaced the clevis pin/cotter pin with a pin with the ball on the side and a keyring loop on the end. A small gauge aircraft cable is attached to that and run over to aft end of steps. I made a loop with a plastic tube as a handle. This is held to the bottom of the rig with a screw with enough slack so step can operate. In a step disaster, you can put a bottle jack under the step to put a little pressure on it to "unload" the step connection. Then you can pull the pin! STAY away from the steps when you do this!
Pull the 4 bolts on the backing plate to the assy and drop assy. Pull the bolts off the backing plate and take the back cover off the gear assy. You will see what to do. The pin that is the axle for the gear is free floating, don't lose it. Flip gear over so hopefully damaged area now is beyond the end of play. After reassembly to backing plate, you can test it on the ground by connecting back to pigtail and cycling the door.
Lube ALL pivot points while steps are free and work it back and forth to get lube to penetrate all points.
KEEP YOUR STEPS LUBED! If you don't hit anything with them, they will function fine for many, many, years.
Safe travels Roger 07VJ S OR coast